Biomass materials contain valuable materials that may be used in a variety of applications such as the production of fuels, feeds and chemicals. The release, segregation and collection of these useful materials are accomplished in the art using a variety of chemical, mechanical and enzymatic processes. Of primary benefit is the release of fermentable sugars such as hexose and pentose that can then be used in the production of biofuels such as ethanol. For these processes to be effective, it is desirable to modify the biomass mechanically and chemically.
Prior art references disclose methods for treating fibers with ammonia. U.S. Pat. No. 4,644,060 discloses a method for increasing the bioavailability of polysaccharide components of ligno-cellulosic materials by treatment with ammonia in a supercritical or near-supercritical fluid state at temperatures ranging from 100 degrees C. to 200 degrees C. and pressures ranging from 6.9 MPa to 35 MPa. Another treatment agent is ethylenediamine that is disclosed as an aid in the removal of lignin in U.S. Pat. No. 5,641,385. U.S. Pat. Nos. 5,171,592 and 5,473,061 and US Pre-Grant Publication number 20080008783 describe methods for exploding biomass by rapidly reducing the pressure at which the biomass is treated, thereby exposing the value components in biomass to swelling agents such as ammonia and amines. These processes require high pressure vessels and are difficult and cumbersome to run cost effectively. Also, these processes tend to destroy some the valuable materials in the fibers such as lignin and hemicelluloses. U.S. Pat. No. 8,444,810 discloses a fiber treatment process in which a mixture of steam, gaseous ammonia and gaseous amine that may contain urea and ethylenediamine is fed through one or more feed ports in the chamber. In one embodiment of U.S. Pat. No. 8,444,810, superheated steam at a temperature in the range of about 140-180° C. and a pressure of about 2 Kilopascals gauge. The steam softens the fiber bundles, which facilitates the macerating action of the pins to separate the fibers while reducing the likelihood of fiber length reduction. While U.S. Pat. No. 8,444,810 presents a substantial simplification relative to the prior art, the high temperature, pressure and the use of chemicals in the treatment vessel are nevertheless a negative aspect that is undesirable.